A conventional superheated vapor generator includes a drum made of metal or other magnetic material. Water or saturated steam is introduced into the drum, which is inductively heated. Another conventional superheated vapor generator includes a drum made of non-magnetic material, in which a magnetic material is buried. Still another conventional superheated vapor generator includes a heating element having holes formed through it. The heating element is coated with metal oxide to prevent oxidation. A further conventional superheated vapor generator includes a heating container filled with paraffin, in which a spiral pipe extends. The paraffin can be heated by an electric heater.
The superheated vapor generators in each of which a drum or a spiral pipe is heated have a heating/conducting area extending over only the inner surface or surfaces of the drum or spiral pipe. Accordingly, the heating/conducting area of these generators is narrow, so that their heating efficiency is low, and so that their heating time is long. In particular, the vapor generator in which paraffin can be heated to heat a spiral pipe cannot generate superheated vapor with a high temperature, which may be 500° C. These vapor generators are not suitable for multi-purpose heating because they cannot generate sufficiently dry vapor but are liable to generate wet steam. The superheated vapor generator including a heating element buried in a non-magnetic material as a coating material is less durable because the hot portion of the coating material deteriorates significantly by being damaged by thermal stress. Each of these vapor generators has an inlet port for water or saturated steam and an outlet port for superheated vapor. Because the inlet and outlet ports are positioned vertically away from each other, the replacement, repair or the like of the heating coil or element involves complex disassembly and assembly operations. The complex operations need to be performed by one or more skilled workers for a long time while the production line is suspended. This greatly influences the productivity.
A superheated vapor generator and a food processor may be installed in a food-processing place, where water is used frequently. It is necessary to separately position the vapor generator and food processor, and to supply superheated vapor from the generator through adiabatic piping to the processor. It is also necessary to take safety measures against electrical leaks and electric shocks. These necessary things raise the cost of equipment.
Patent Document 1: Japanese Unexamined Patent Publication No. H9-4803
Patent Document 2: Japanese Unexamined Patent Publication No. 2003-100427
Patent Document 3: Japanese Patent No. 2999228